Surgical stapling and cutting instruments have been used in the prior art to simultaneously make an incision in tissue and apply lines of staples on opposing sides of the incision. End effectors of such instruments commonly include a pair of cooperating jaw members that, if the instrument is intended for endoscopic or laparoscopic applications, are capable of passing through a cannula passageway. One of the jaw members generally receives a staple cartridge having at least two laterally spaced rows of staples. The other jaw member defines an anvil having staple-forming pockets aligned with the rows of staples in the cartridge. The instrument includes a plurality of reciprocating wedges which, when driven distally, pass through openings in the staple cartridge and engage drivers supporting the staples to effect the firing of the staples toward the anvil.
It is often advantageous to build a reusable end effector for the surgical stapler. For instance, one patient may need a series of severing and stapling operations. Replacing an entire end effector for each operation tends to be economically inefficient. This is especially true if the end effector is built for strength and reliability for repeated operations. To that end, staple cartridges are fitted into the end effector prior to each operation of the surgical stapler.
While the staple cartridge containing staples provides numerous advantages, it is desirable to prevent inadvertent firing of the instrument when it is not properly aligned with and does not clamp the tissue properly. Moreover, for ease of manufacturing and assembly, it is further desirable that the lockout features be accomplished with a minimum number of components.
Consequently, a significant need exists for improved lockout mechanisms for surgical stapling and cutting instruments, particularly in linear staplers, that prevent firing when the instrument or stapler is not aligned to clamp the tissue properly.